Hull builder can now build hulls including various validations.

src/sconvcol.h

@@ -9,6 +9,10 @@ extern "C" {
 #include <stdbool.h>
 
 #include "vectorial/simd4x4f.h"
+8
+inline bool sch_simd4f_equal(simd4f a, simd4f b) {
+  return (simd4f_get_x(simd4f_length4_squared(simd4f_sub(a, b))) == 0.f);
+}
 
 typedef struct sch_edge sch_edge;
 typedef struct sch_vert sch_vert;
@@ -35,10 +39,12 @@ struct sch_face {
 };
 
 struct sch_hull {
-  int num_faces;
   sch_face* faces;
   sch_edge* edges;
   sch_vert* vertices;
+  int num_faces;
+  int num_edges;
+  int num_vertices;
 };
 
 struct sch_plane {
@@ -64,7 +70,10 @@ struct sch_face_query {
 
 enum SchHullResult {
   SchHullResultOK = 0,
-  SchHullResultConcaveVertex = -1
+  SchHullResultConcaveVertex = -1,
+  SchHullResultWrongWinding = -2,
+  SchHullResultInvalidTwinEdges = -3,
+  SchHullResultOpenHull = -4
 };
 
 typedef enum SchHullResult SchHullResult;
@@ -98,21 +107,20 @@ void sch_edge_get_dir(sch_edge* edge, simd4f* dir);
 
 void sch_hull_free_memory (sch_hull* hull);
 
-void sch_hull_get_plane(const sch_hull* hull, int index, sch_plane* out_plane);
+void sch_hull_get_plane(const sch_hull* hull, const int index, sch_plane* out_plane);
+
+sch_edge* sch_hull_find_edge (const sch_hull* hull, const simd4f v0, const simd4f v1);
 
 void sch_hull_get_support(const sch_hull* hull, simd4f n, simd4f* out_vert);
 
-int sch_hull_is_vertex_concave(const sch_hull* hull, simd4f p);
+int sch_hull_is_vertex_concave(const sch_hull* hull, const simd4f p);
+
+int sch_hull_is_closed (const sch_hull* hull);
+
+int sch_hull_connect_face_edges(const sch_hull* hull, int face_index);
 
 void sch_create_face(int num_vert, simd4f* vertices, sch_face* out_face);
 
-SchHullResult sch_create_hull(int num_faces, sch_face* faces, sch_hull* out_hull);
-
-void sch_query_face_dir(
-    const sch_hull* hull_A,
-    const sch_hull* hull_B,
-    sch_face_query* out_query);
-
 //
 // sconvcol Implementation
 //
@@ -162,7 +170,12 @@ void sch_builder_reset(sch_hull_builder* builder) {
 
 void sch_builder_face_begin(sch_hull_builder* builder) {
   int face_index = builder->num_faces;
-  builder->face_vert_idx_start[face_index] = builder->num_vertices;
+  if (builder->num_faces == 0) {
+    builder->face_vert_idx_start[face_index] = 0;
+  } else {
+    builder->face_vert_idx_start[face_index] = builder->face_vert_idx_end[face_index - 1] + 1;
+  }
+
   builder->face_vert_idx_end[face_index] = -1;
 }
 
@@ -171,37 +184,41 @@ void sch_builder_face_end(sch_hull_builder* builder) { builder->num_faces++; }
 void sch_builder_allocate_memory (sch_hull_builder* builder, sch_hull* out_hull) {
   out_hull->faces = (sch_face*)malloc(sizeof(sch_face) * builder->num_faces);
 
+  out_hull->num_vertices = builder->num_vertices;
   out_hull->vertices =
       (sch_vert*)malloc(sizeof(sch_vert) * builder->num_vertices);
 
-  int num_edges = 1;
+  int num_edges = 0;
   for (int face_index = 0; face_index < builder->num_faces; face_index++) {
     int start_idx = builder->face_vert_idx_start[face_index];
     int end_idx = builder->face_vert_idx_end[face_index];
     int edge_count = end_idx - start_idx;
 
-    num_edges += edge_count;
+    num_edges += edge_count + 1;
   }
 
+  out_hull->num_edges = num_edges;
   out_hull->edges = (sch_edge*)malloc(sizeof(sch_edge) * num_edges);
 }
 
 void sch_hull_free_memory (sch_hull* hull) {
   free (hull->faces);
   hull->faces = NULL;
+  hull->num_faces = 0;
   free (hull->vertices);
   hull->vertices = NULL;
+  hull->num_vertices = 0;
   free (hull->edges);
   hull->edges = NULL;
+  hull->num_edges = 0;
 }
 
 SchHullResult sch_builder_create_hull(sch_hull_builder* builder, sch_hull* out_hull) {
   sch_builder_allocate_memory(builder, out_hull);
+  out_hull->num_faces = 0;
 
   int hull_edge_idx = 0;
 
-  out_hull->num_faces = 0;
-
   for (int face_index = 0; face_index < builder->num_faces; face_index++) {
     sch_face* face = &out_hull->faces[face_index];
 
@@ -242,10 +259,18 @@ SchHullResult sch_builder_create_hull(sch_hull_builder* builder, sch_hull* out_h
       prev_edge = edge;
     }
 
+    int edge_add_result = sch_hull_connect_face_edges (out_hull, face_index);
+    if (edge_add_result != SchHullResultOK) {
+      sch_hull_free_memory(out_hull);
+      return edge_add_result;
+    }
+
     out_hull->num_faces = face_index + 1;
   }
 
-  return SchHullResultOK;
+  assert (hull_edge_idx == out_hull->num_edges);
+
+  return sch_hull_is_closed (out_hull);
 }
 
 void sch_builder_face_vertex(sch_hull_builder* builder, simd4f vertex) {
@@ -277,7 +302,7 @@ void sch_builder_face_vertex(sch_hull_builder* builder, simd4f vertex) {
   builder->face_vert_idx[face_end_idx] = vert_index;
 }
 
-void sch_hull_get_plane(const sch_hull* hull, int index, sch_plane* out_plane) {
+void sch_hull_get_plane(const sch_hull* hull, const int index, sch_plane* out_plane) {
   assert(hull != NULL);
   assert(index >= 0 && index < hull->num_faces);
   assert(out_plane != NULL);
@@ -295,7 +320,24 @@ void sch_hull_get_plane(const sch_hull* hull, int index, sch_plane* out_plane) {
   out_plane->n = simd4f_cross3(dir0, dir1);
 }
 
-int sch_hull_is_vertex_concave(const sch_hull* hull, simd4f v) {
+sch_edge* sch_hull_find_edge (const sch_hull* hull, const simd4f v0, const simd4f v1) {
+  for (int fi = 0; fi < hull->num_faces; fi++) {
+    sch_face* face = &hull->faces[fi];
+    sch_edge* edge0 = face->edge;
+    sch_edge* edge = edge0;
+    do {
+      if (sch_simd4f_equal(edge->vert->p, v0)
+          && sch_simd4f_equal(edge->next->vert->p, v1)) {
+        return edge;
+      }
+      edge = edge->next;
+    } while (edge != edge0);
+  }
+
+  return NULL;
+}
+
+int sch_hull_is_vertex_concave(const sch_hull* hull, const simd4f v) {
   sch_plane plane;
   for (int i = 0; i < hull->num_faces; i++) {
     sch_hull_get_plane(hull, i, &plane);
@@ -306,40 +348,63 @@ int sch_hull_is_vertex_concave(const sch_hull* hull, simd4f v) {
   return 0;
 }
 
-sch_hull* sch_create_box() {
+int sch_hull_connect_face_edges(const sch_hull* hull, int new_face_index) {
-  simd4f vertices_pos_z[4] = {
+  sch_face* new_face = &hull->faces[new_face_index];
-      simd4f_create(-0.5f, -0.5f, 0.5f, 0.f),
-      simd4f_create(0.5f, -0.5f, 0.5f, 0.f),
-      simd4f_create(0.5f, 0.5f, 0.5f, 0.f),
-      simd4f_create(-0.5f, 0.5f, 0.5f, 0.f)};
-  sch_face face_pos_z = {0};
-  sch_create_face(4, vertices_pos_z, &face_pos_z);
 
-  simd4f vertices_neg_z[4] = {
+  sch_edge* new_face_edge0 = new_face->edge;
-      simd4f_create(-0.5f, -0.5f, -0.5f, 0.f),
+  sch_edge* new_face_edge = new_face_edge0;
-      simd4f_create(0.5f, -0.5f, -0.5f, 0.f),
-      simd4f_create(0.5f, 0.5f, -0.5f, 0.f),
-      simd4f_create(-0.5f, 0.5f, -0.5f, 0.f)};
-  sch_face face_neg_z = {0};
-  sch_create_face(4, vertices_neg_z, &face_neg_z);
 
-  simd4f vertices_pos_x[4] = {
+  do {
-      simd4f_create(0.5f, -0.5f, 0.5f, 0.f),
+    sch_vert* new_edge_v0 = new_face_edge->vert;
-      simd4f_create(0.5f, -0.5f, -0.5f, 0.f),
+    sch_vert* new_edge_v1 = new_face_edge->next->vert;
-      simd4f_create(0.5f, 0.5f, -0.5f, 0.f),
-      simd4f_create(0.5f, 0.5f, 0.5f, 0.f)};
 
-  sch_face face_pos_x = {0};
+    for (int fi = 0; fi < hull->num_faces; fi++) {
-  sch_create_face(4, vertices_pos_x, &face_pos_x);
+      if (fi == new_face_index) {
+        continue;
+      }
 
-  simd4f vertices_neg_x[4] = {
+      sch_face* face = &hull->faces[fi];
-      simd4f_create(-0.5f, -0.5f, 0.5f, 0.f),
+      sch_edge* face_edge0 = face->edge;
-      simd4f_create(-0.5f, -0.5f, -0.5f, 0.f),
+      sch_edge* face_edge = face_edge0;
-      simd4f_create(-0.5f, 0.5f, -0.5f, 0.f),
-      simd4f_create(-0.5f, 0.5f, 0.5f, 0.f)};
 
-  sch_face face_neg_x = {0};
+      do {
-  sch_create_face(4, vertices_neg_x, &face_neg_x);
+        sch_vert* edge_v0 = face_edge->vert;
+        sch_vert* edge_v1 = face_edge->next->vert;
+
+        if (sch_simd4f_equal(new_edge_v0->p, edge_v0->p)
+            && sch_simd4f_equal(new_edge_v1->p, edge_v1->p)) {
+          return SchHullResultWrongWinding;
+        } else if (sch_simd4f_equal(new_edge_v0->p, edge_v1->p)
+                              && sch_simd4f_equal(new_edge_v1->p, edge_v0->p)) {
+          if (new_face_edge->twin == NULL && face_edge->twin == NULL) {
+            new_face_edge->twin = face_edge;
+            face_edge->twin = new_face_edge;
+          } else if (new_face_edge->twin == face_edge->twin) {
+            // nothing to do
+          } else if ((new_face_edge->twin == NULL && face_edge->twin != NULL)
+              || (new_face_edge->twin != NULL && face_edge->twin == NULL)) {
+            return SchHullResultInvalidTwinEdges;
+          }
+        }
+
+        face_edge = face_edge->next;
+      } while (face_edge != face_edge0);
+    }
+
+    new_face_edge = new_face_edge->next;
+  } while (new_face_edge != new_face_edge0);
+
+  return SchHullResultOK;
+}
+
+int sch_hull_is_closed (const sch_hull* hull) {
+  for (int ei = 0; ei < hull->num_edges; ei++) {
+    if (hull->edges[ei].twin == NULL) {
+      return SchHullResultOpenHull;
+    }
+  }
+
+  return SchHullResultOK;
 }
 
 #endif /* SCONVCOL_IMPLEMENTATION */

tests/sconvcolTests.cc

@@ -3,10 +3,6 @@
 #include "catch.hpp"
 #include "sconvcol.h"
 
-bool simd4f_equal(simd4f a, simd4f b) {
-  return (simd4f_get_x(simd4f_length4_squared(simd4f_sub(a, b))) == 0.f);
-}
-
 using namespace std;
 
 TEST_CASE("Plane Distance", "[sconvcol]") {
@@ -70,12 +66,13 @@ TEST_CASE("HullBuilder", "[sconvcol]") {
   GIVEN("An empty builder") {
     sch_builder_reset(&builder);
 
-    WHEN("adding two vertices ") {
     simd4f vertex0 = simd4f_create(0.f, 0.f, 0.f, 1.f);
+    simd4f vertex1 = simd4f_create(1.f, 0.f, 0.f, 1.f);
+    simd4f vertex2 = simd4f_create(0.5f, 1.f, 0.f, 1.f);
+
+    WHEN("adding two vertices ") {
       sch_builder_face_begin(&builder);
       sch_builder_face_vertex(&builder, vertex0);
-
-      simd4f vertex1 = simd4f_create(1.f, 0.f, 0.f, 1.f);
       sch_builder_face_vertex(&builder, vertex1);
 
       WHEN("ending the face") {
@@ -89,7 +86,6 @@ TEST_CASE("HullBuilder", "[sconvcol]") {
       }
 
       WHEN("creating a triangle") {
-        simd4f vertex2 = simd4f_create(0.5f, 1.f, 0.f, 1.f);
         sch_builder_face_vertex(&builder, vertex2);
         sch_builder_face_end(&builder);
 
@@ -105,7 +101,7 @@ TEST_CASE("HullBuilder", "[sconvcol]") {
           SchHullResult result = sch_builder_create_hull(&builder, &hull);
 
           THEN("verify triangle hull") {
-            REQUIRE(result == SchHullResultOK);
+            REQUIRE(result == SchHullResultOpenHull);
             REQUIRE(hull.num_faces == 1);
             sch_face* face = &hull.faces[0];
 
@@ -113,9 +109,9 @@ TEST_CASE("HullBuilder", "[sconvcol]") {
             sch_vert* hull_vert1 = face->edge->next->vert;
             sch_vert* hull_vert2 = face->edge->next->next->vert;
 
-            REQUIRE(simd4f_equal(hull_vert0->p, vertex0));
+            REQUIRE(sch_simd4f_equal(hull_vert0->p, vertex0));
-            REQUIRE(simd4f_equal(hull_vert1->p, vertex1));
+            REQUIRE(sch_simd4f_equal(hull_vert1->p, vertex1));
-            REQUIRE(simd4f_equal(hull_vert2->p, vertex2));
+            REQUIRE(sch_simd4f_equal(hull_vert2->p, vertex2));
 
             REQUIRE(face->edge->next->next->next == face->edge);
           }
@@ -145,12 +141,99 @@ TEST_CASE("HullBuilder", "[sconvcol]") {
           }
 
           THEN("hull creation fails") {
-            SchHullResult result = sch_builder_create_hull(&builder, &hull);
+            sch_hull concave_hull;
+            SchHullResult result = sch_builder_create_hull(&builder, &concave_hull);
+
             REQUIRE(result == SchHullResultConcaveVertex);
+
+            sch_hull_free_memory(&concave_hull);
           }
 
           sch_hull_free_memory(&hull);
         }
+
+        WHEN("adding adjacent clockwise winded face") {
+          simd4f vertex4 = simd4f_create(0.5f, -0.25f, 0, 1.f);
+
+          sch_builder_face_begin(&builder);
+          sch_builder_face_vertex(&builder, vertex0);
+          sch_builder_face_vertex(&builder, vertex1);
+          sch_builder_face_vertex(&builder, vertex4);
+          sch_builder_face_end(&builder);
+
+          THEN("hull creation fails") {
+            sch_hull hull;
+            SchHullResult result = sch_builder_create_hull(&builder, &hull);
+
+            REQUIRE(result == SchHullResultWrongWinding);
+
+            sch_hull_free_memory(&hull);
+          }
+        }
+
+        WHEN("adding adjacent counter clockwise winded face") {
+          simd4f vertex4 = simd4f_create(0.5f, -0.25f, 0, 1.f);
+
+          sch_builder_face_begin(&builder);
+          sch_builder_face_vertex(&builder, vertex0);
+          sch_builder_face_vertex(&builder, vertex4);
+          sch_builder_face_vertex(&builder, vertex1);
+          sch_builder_face_end(&builder);
+
+          THEN("edge v0-v1 has twin edge v1-v0") {
+            sch_hull hull;
+            SchHullResult result = sch_builder_create_hull(&builder, &hull);
+
+            REQUIRE(result == SchHullResultOpenHull);
+
+            sch_edge* edge_v0_v1 = sch_hull_find_edge(&hull, vertex0, vertex1);
+            sch_edge* edge_v1_v0 = sch_hull_find_edge(&hull, vertex1, vertex0);
+
+            REQUIRE (edge_v0_v1 != NULL);
+            REQUIRE (edge_v1_v0->twin == edge_v0_v1);
+
+            sch_hull_free_memory(&hull);
+          }
+        }
+      }
+    }
+
+    WHEN("creating a tetrahedron ") {
+      simd4f vertex3 = simd4f_create (0.5f, 0.f, -0.5f, 1.f);
+
+      // +z facing triangle
+      sch_builder_face_begin(&builder);
+      sch_builder_face_vertex(&builder, vertex0);
+      sch_builder_face_vertex(&builder, vertex1);
+      sch_builder_face_vertex(&builder, vertex2);
+      sch_builder_face_end(&builder);
+
+      // +x,-z facing triangle
+      sch_builder_face_begin(&builder);
+      sch_builder_face_vertex(&builder, vertex1);
+      sch_builder_face_vertex(&builder, vertex3);
+      sch_builder_face_vertex(&builder, vertex2);
+      sch_builder_face_end(&builder);
+
+      // -x,-z facing triangle
+      sch_builder_face_begin(&builder);
+      sch_builder_face_vertex(&builder, vertex0);
+      sch_builder_face_vertex(&builder, vertex2);
+      sch_builder_face_vertex(&builder, vertex3);
+      sch_builder_face_end(&builder);
+
+      // -y facing triangle
+      sch_builder_face_begin(&builder);
+      sch_builder_face_vertex(&builder, vertex0);
+      sch_builder_face_vertex(&builder, vertex3);
+      sch_builder_face_vertex(&builder, vertex1);
+      sch_builder_face_end(&builder);
+
+      THEN("results in a closed hull") {
+        sch_hull hull;
+        SchHullResult result = sch_builder_create_hull(&builder, &hull);
+        REQUIRE (result == SchHullResultOK);
+        sch_hull_free_memory(&hull);
       }
     }
   }